#include <cstdio>
using namespace std;

#define BUF_SIZE 1024

int main()
{
    char s1[BUF_SIZE], s2[BUF_SIZE];
    scanf(" %s", s1);
    scanf(" %s", s2);

    char *i, *j;
    for (i = s1, j = s2; *i != '\0' && *j != '\0'; i++, j++) {
        if (*i != *j)
            printf("%d", *i - *j);
    }

    return 0;
}